The present invention is concerned with a rotor unit for a centrifugal analyzer with a rotor base connected with a drive and a rotor head which, in operation, is connected with the rotor base. The rotor head includes chambers for the reception of a sample liquid and, radially outwardly from the associated sample chambers, measuring chambers for the measurement of characteristic parameters for the detection of components of the sample, as well as liquid channels for connecting the sample chambers with the measuring chambers. The present invention is also concerned with insert elements and a centrifugal analyzer which are adapted for use with the rotor unit according to the present invention.
Centrifugal analyzers with a rotor unit of the above-mentioned type have been conventional for a number of years for the purposes of chemical analysis, especially in clinical chemistry. They have circularly symmetrically constructed rotor units with a plurality of radial analysis channels. Usually, each analysis channel has, from the inside towards the outside, a trough-shaped reagent space, a sample space and a measuring space which, in the case of the known devices, is constructed as an optical cuvette. The rotor unit can be arranged in a rotor base and a rotor head mounted non-rotatably on the rotor base. The rotor base is usually constructed as a plate or frame and securely attached to the axis of the rotor drive. The term "rotor head" designates the remaining part of the rotor unit which, in particular, includes the above-mentioned analysis channels. In the case of more recent centrifugal analyzers, the rotor head is, as a unit, exchangeable and is, in operation, non-rotatably connected with the rotor base. The rotor head and the rotor base can, in each case, be constructed in a large variety of ways and can also differ substantially, especially in the diameter of their outer boundary. Thus, the rotor base can, for example, consist of only a holder for the rotor head connected in one piece with the rotor drive axis, which holder, is, in operation, completely superimposed by the rotor head.
In the case of the known devices, the rotor head is, while stationary, filled with reagents and samples. A device which can be used for this purpose is described in Federal Republic of Germany Pat. Specification No. 2,626,810, which also describes the construction of a typical rotor. As is to be seen from this German Patent Specification, a complicated mechanical device is needed for automatically filling the rotor.
After filling, the known rotor heads are placed in the centrifugal analyzer and connected with the rotor base. The rotor is set in rapid rotation and, in the case of some devices of this kind, alternating speeds of rotation are used for mixing. Due to the centrifugal acceleration during rotation of the rotor, the reagent passes from its chamber into the sample chamber and then the two together are passed into the measuring chamber, measurement there being carried out with the rotor running. In the case of the known devices, the measurement consists of a determination of the optical density of the liquid in the measuring chambers, which are constructed as optical cuvettes. Thanks to modern electronic evaluation devices, the absorption can be measured in each cuvette at each rotation of the rotor. In this way, the absorption in all cuvettes can be observed almost continuously. In the case of a typical rotational speed of 1000 rotations per minute, 1000 measurements are carried out per minute for each cuvette. On the basis of this process, there is obtained a precision of measurement which, in the case of comparable analysis frequency, can scarely be achieved with conventional analysis devices, especially in the case of so-called kinetic analysis determinations in which the speed of the course of the reaction permits conclusions to be made regarding the concentration of a particular component.
The known centrifugal analyzers have a number of important advantages but also considerable disadvantages. A summary of the most important requirements for an optimum analysis device can be found in one of the first publications concerning centrifugal analyzers (see Norman G. Anderson in "Analytical Biochemistry", 28, 545-562/1969). One of these requirements is the practically simultaneous measurement of several reactions which, as described above, make possible a better monitoring of the individual courses of reaction. Another requirement is that the volumes of the reagents and samples should be as small as possible. This requirement is also substantially fulfilled by the known centrifugal analyzers but an improvement is still desirable. Centrifugal analyzers readily permit the attachment of modern data evaluation systems for the evaluation of the measurement results, i.e. not only for the conversion of the absorption values into the desired concentration values but also the statistical evaluation of these concentrations in order to give the physician information which is prepared as far as possible.
Other requirements already mentioned in this early article by Anderson are not fulfilled to a desirable extent by the centrifugal analyzers which are at the moment conventional. The known devices still require a large amount of attention from personnel, they are not sufficiently simple to enable them also to be used by untrained personnel and they are not yet sufficiently flexible and variable in order to be able to fulfill very different requirements, especially in the operation of a clinical laboratory.
These deficiencies have, in the course of time, given rise to a large number of developments of the original concept, which have led to increasingly complicated rotor constructions. Thus, these rotors were expensive to produce but are still not able to fulfill all the various requirements of the different analytical determinations which are usual in clincal chemistry.
In particular, the known rotors can only be used for carrying out one analytical determination for a number of samples in one run of the rotor. As a rule, however, in the clinical laboratory a series of different analytical determinations must be carried out on a sample, for example blood from a patient, which, in toto, are also called the profile. In the case of the known analyzers, this necessitates a considerable amount of organization. Thus, the individually necessary analytical determinations, communicated, for example, by the physician to the clinical laboratory, must be carried out gradually in separate rotor runnings on one or more centrifugal analyzers. Thereafter, the separately determined data must be collated and passed on to the physician. This complicated procedure not only requires a considerable amount of organization but is, unfortunately, not infrequently the cause of errors of communication which can possible result in false therapeutic measures being carried out by the physician. Thus, there is a need for centrifugal analyzers which can be adapted more variably and flexibly to various tasks and which, in particular, can be used for profile analyses or at least for several different analytical determinations in one rotor running. This is especially necessary for emergency analyses where, under certain circumstances, several different analytical determinations must be carried out in the shortest possible time for one sample, i.e. for one patient.
Another problem of clinical chemistry which is not only typical for centrifugal analyzers is that, in the case of the known devices, obtaining the sample, i.e. especially obtaining serum or plasma from blood, and preparing the sample, i.e. especially diluting serum or plasma to the concentrations necessary for the analysis, take place in separate working steps away from the analysis device. It is readily apparent that, in this way, additional manual working steps and, in particular, decanting steps are necessary. These can, in turn, again result in mistakes being made or can, for example, also result in contamination of the samples.